Hexane extract from Uncaria sinensis exhibits anti-apoptotic properties against glutamate-induced neurotoxicity in primary cultured cortical neurons

Abstract

We explored the neuroprotective effects of a hexane extract from Uncaria sinensis (HEUS) against glutamate-induced toxicity focusing on its anti-apoptotic mechanism in primary cultured cortical neurons. Pretreatment with HEUS resulted in significantly reduced glutamate-induced toxicity in a dose-dependent manner with a decrease in the release of lactate dehydrogenase. Morphological assay and flow cytometry were performed for determination of the type of cell death; according to the results, treatment with HEUS resulted in a significant reduction of glutamate-induced apoptotic cell death. We examined the anti-apoptotic mechanism of HEUS; treatment with HEUS resulted in markedly decreased expression of death receptor (DR)4, which was induced by glutamate stimulation. In contrast, treatment with HEUS resulted in significantly enhanced levels of expression of glutamate-attenuated XIAP and Bcl-2, as well as marked blockade of glutamate-induced Bid cleavage, which inhibits both extrinsic and intrinsic apoptosis pathways. In addition, pretreatment with HEUS resulted in almost complete blockade of glutamate-induced activation of caspases-8, -9 and -3, as well as cleavage of poly (ADP-ribose) polymerase. These findings suggest that the neuroprotective effects of HEUS against glutamate-induced toxicity occur via inhibition of DR4 and expression of anti-apoptotic proteins XIAP and Bcl-2 resulting in effective abrogation of the activation of caspase cascades and promotion of cell survival.

Neuroprotective Effects of a Novel Single Compound 1-Methoxyoctadecan-1-ol Isolated from Uncaria sinensis in Primary Cortical Neurons and a Photothrombotic Ischemia Model

“…Pretreatment with 1-methoxyoctadecan-1-ol resulted in concentration-dependent inhibition of glutamate-induced toxicity (Fig. 2) and prevention more specifically at a very lower dose, compared with our previous studies [6]. Exposure to excitotoxic levels of glutamate induces two distinct types of programmed cell death, sharing both necrosis and apoptosis [19].…”

“…p38 MAPK plays an integral role in caspase activation and mitochondrial dysfunction by Bcl-2 family [38], [39] and blocking via the PI3K/Akt signaling pathway with downstream effector Bcl-2 [40], [41]. Our previous results showing that hexane extract from U. sinensis enhanced Bcl-2 expression with alleviation of caspase activation [6] may suggest possible involvement of another pathway. However, Western blot analysis showed that co-treatment resulted in complete blockade of all activated calpain, STEP cleavage, and p38 phosphorylation, in which methoxyoctadecan-1-ol exerted neuroprotective effects similar to those of calpeptin.…”

“…Because hexane extract from U. sinensis exhibits anti-apoptotic effects [6], this extract may be an attractive candidate for use as a therapeutic compound for treatment of neurodegenerative diseases associated with excitotoxicity. We isolated a novel neuroprotectant, 1-methoxyoctadecan-1-ol, from U. sinensis (Fig.…”

“…Our previous results demonstrated that a hexane extract from U. sinensis protects against cerebral ischemic damage through regulation of Akt/endothelial nitric oxide synthase signaling [5] and exerts significant anti-apoptotic effects against glutamate-induced neurotoxicity [6]. Because it has not been determined which compounds of U. sinensis are bioactive, we isolated a novel single compound, 1-methoxyoctadecan-1-ol, from specific fractions of hexane extracts using an neuronal cells and ischemic animal model for screening of active constituents.…”

Effects of standardized extract of Ferula gummosa root on glutamate-induced neurotoxicity

“…One way to reduce glutamate toxicity is to use antioxidant compounds such as medicinal plants. Recent studies have shown some herbal medicines have protective effects against glutamate such as peel and seed extract of Citrus aurantium [16], Persea major [8], Uncaria sinensis [20], Scrophularia striata Boiss [36], and Withania somnifera [22]. In this research, we used Ferula gummosa extract against glutamate toxicity in two cell lines: PC12 and N2a.…”